Offshore wind turbines aren’t louder than high winds or passing ships, no evidence they harm whales

About 9% of wind power newly connected to electrical grids in 2023 came from offshore wind turbines – by 2033, that proportion could surpass 25%.

Although it’s more costly to install wind turbines out at sea than on land, offshore wind does have a few key advantages. Winds are usually stronger out at sea, so turbines of the same size installed offshore can generate more electricity. What’s more, because offshore turbines are generally farther away from civilization, we can build taller turbines with less resistance from people who don’t want turbines near their homes.  

But less opposition does not mean no opposition – especially in the U.S., where offshore wind developers have faced fierce backlash from politicians and anti-wind campaigners. Where opposition to onshore wind often revolves around turbines’ supposed effects on human health, opposition to offshore wind must turn to different claims. A common one is that the noise that offshore wind turbines make, or the noise we must make in order to build them, is harmful to marine life like whales. The most prominent purveyor of these claims may be incoming U.S. president Donald Trump, who has repeatedly claimed that “windmills” are driving whales “crazy” and killing whales “in numbers never seen before”. 

Science Feedback has previously reviewed similar claims, but these kinds of claims continue to circulate. So, what does science actually say on the matter? Below, we’ll look at some of the most common claims linking offshore wind and whales – as we’ll show, there’s a lack of evidence to support that offshore wind turbines have inflicted any actual harm to whales.

Wind turbines are quieter than ships

Wind turbines are large machines, and their moving parts – like their blades – aren’t silent. Although a wind turbine’s blades spin in the air, their vibrations spread down the turbine shaft and out through the water^[1]. Offshore wind’s critics, like Trump, claim that this noise is a severe disturbance to underwater animals that can hear it – like whales. Extreme versions of this claim, like those in this Epoch Times article, even suggest that the noise can deter whales from migrating and drive some whale populations into extinction. 

Wind turbines do make noise, but evidence suggests that underwater listeners – including whales – can’t hear them when other noise is present, like the sounds of large ships. In the real world, measurements of noise near turbines in Europe’s North Sea and the North Atlantic, at different distances up to 1 kilometer (0.6 miles) away, have shown that turbine noise is usually quieter underwater than noise from ships at a comparable distance (Figure 1)^[1].

For a U.S. example, University of Rhode Island researchers measured the sound from Block Island Wind Farm after it became the first U.S. offshore wind project to start generating electricity in December 2015. At a distance of just 50 meters (164 feet), Block Island’s turbines were quiet enough that a whale could not detect their sound over the sounds of passing ships, wind, and other background noise. At greater distances, a whale could not hear turbines even on quiet days.

Computer simulations of wind farm noise have similar results. A 2020 study modeled the noise from several models of offshore wind turbines commonly found in northern Europe. The authors simulated the noise from wind farms of up to 81 turbines in a single location. In quiet seas, simulated wind farms were audible underwater up to several kilometers, but in seas with ship traffic or high winds – the very winds that turbines are generally intended to catch – the turbines were quieter than ambient noise at all but the closest distances, less than 50 meters (164 feet)^[1].

There are very real reasons to be concerned about human-made noise in the oceans – noise can drown out the sounds that whales use to communicate and to navigate, and loud enough noise can even cause hearing loss^[2]. But it is misleading to single out wind turbines as a strong disruption, when the evidence we do have instead indicates that wind turbine noise tends to fade into the backdrop.

Other sources of noise aren’t as disruptive as claimed

Of course, when we talk about an offshore wind turbine’s noise, we must look across a turbine’s entire life cycle and talk about the noise we make in order to build it. For example, renewable energy critic Michael Shellenberger has claimed – in a video that Science Feedback has reviewed – that the acoustic surveys used to study possible wind turbine sites are disturbing whales. However, there’s no convincing evidence to support this.

Before any wind turbine can be built offshore, its operators usually must survey the seafloor. These surveys often map the seafloor by broadcasting sound underwater, similar to the sonar used by submarines – the seafloor reflects the sound, and we can study the reflected sound to make a map. There is evidence that strong enough sonar can harm whales, but scientists do not believe the kinds of surveys used for wind energy constitute strong enough sonar. Moreover, the sound is non-impulsive, meaning it doesn’t contain sudden, sharp sounds (which we might hear as clicks, bangs, or pops)^[3].

Additionally, the sound used for wind energy surveys is much lower-energy and much less disruptive than the seismic airguns often used to survey for offshore oil and gas. These airguns are significantly louder – as oil and gas are frequently found deep under the sea floor, they need to use stronger sound pulses – and their noise is often impulsive (meaning it can contain startling, disruptive sounds).

Other claims concern the noise associated with constructing wind turbines – the most common being the noise from hammering a wind turbine’s foundation piles into the seafloor. However, it’s already common practice to mitigate this type of noise with devices like bubble curtains – silencing shrouds that wrap around a turbine construction site. A few European countries already mandate the use of such mitigations. Offshore wind projects in Germany, for example, must keep their sound under a mandatory legal threshold.

What does this look like in practice? Vineyard Wind (a wind project that is, as of this writing, under construction off the Massachusetts coast) agreed to a list of mitigation measures to get a construction permit from the U.S. government. Vineyard Wind can only carry out construction at times of year when whales or dolphins are not migrating through the area. Even when construction is ongoing, workers must quiet pile-driving nose with devices like bubble curtains. Workers must watch the surrounding seas for whales and stop work if any whales approach. Ships servicing the wind farm must also watch for whales and slow down when they see one.

Many scientists explain that such mitigation measures are a good way to balance humans’ energy needs with whales’ well-being. Erin Meyer-Gutbrod of the University of South Carolina told Science Feedback:

“Offshore wind has the potential to increase risk for right whales and other marine mammals in the area due to increases in vessel traffic and anthropogenic noise.  However, I also think offshore wind is an important part of our nation’s portfolio for transitioning to renewable energy. Risks to marine mammals can be mitigated by slowing down vessels, carefully timing construction activities, and implementing noise reduction technologies. Appropriate application of risk reduction strategies will be best supported by robust monitoring for threatened species like right whales.”

Ship collisions and fishing equipment, not wind turbines, cause harm to whales

The U.S. National Oceanic and Atmospheric Administration (NOAA) has tracked unusually high levels of humpback whales stranded on North America’s shores since 2016 and North Atlantic right whales since 2017. Some wind energy opponents have blamed offshore turbines for these dead and injured whales. So what exactly is behind these events?

There isn’t a single clear answer – it’s not always easy to discern the cause of a whale casualty, particularly if a dead whale’s body has already started decomposing. That said, statistics from whales that have been examined largely blame one of two causes: whales being struck by ships (known as “vessel strikes”) and whales getting caught in fishing equipment (known as “entanglements”). 

NOAA has recorded 148 dead or injured North Atlantic right whales since 2017. 30 right whale deaths have been examined, and 25 of those have been attributed to entanglements or vessel strikes. Similarly, of 107 injured whales, 86 can be attributed to entanglements and 10 to vessel strikes. None of these deaths or injuries can be pinned on offshore wind turbines (Figure 2). While offshore wind needs boats, so do many other maritime activities, and there’s no evidence that offshore wind is directly responsible for any of these whale casualties.

Likewise, NOAA has recorded 232 humpback whale deaths on or near the U.S. Atlantic coast since 2016. About 90 of those whales have been thoroughly examined, and 40% of their deaths have been attributed to human actions – either being struck by a ship or getting caught up in a net. From a scientific perspective, this data is not surprising – researchers have long known that both vessel strikes^[4] and entanglements^[5] are dangerous to whales.

On the other hand, there is again no evidence that offshore wind is responsible, and it’s baseless to claim otherwise.

There is research into How wind turbines affect whales, but claims do not align with the research findings

Scientists still have unanswered questions – for example, how exactly whales respond to construction noises or how wind turbines might move the plankton upon which whales feed. There are many reasons to be concerned about how whales are faring. Whale populations are not large, and even a few dozen casualties can be devastating. Take the North Atlantic right whale, which we previously discussed. It’s an endangered species, and its population has fluctuated: rising from about 318 in 2000 to about 477 in 2010, then falling to about 431 in 2017 and about 370 in 2023.

But it should be noted that some of the groups opposing offshore wind with the intent of “saving the whales”, even if they appear to be community organizations or think tanks, are actually backed by the fossil fuel industry. Some groups have directly accepted money from fossil fuel interests, while others might share people or legal support. The report says: 

“They appear to be new organizations that operate organically and independently, but they often share legal support, personnel, talking points, and financial resources with major organizations that have been blocking climate policy for the last several decades.”

It is not in whales’ best interest to oppose offshore wind while defending fossil fuels. If protecting whales means addressing the human activities that are actually harming whales, then it means addressing a factor that touches whales everywhere in the world’s oceans: climate change driven by emissions from human activities. Climate change is causing Earth’s oceans to warm (Figure 3), including in the North Atlantic, and to become more acidic^[6]. These changes can shift where and when whales migrate^[7]. And rising water temperatures can kill plankton, a major source of whale food.

The primary cause of climate change is the greenhouse gas emissions from human activities – such as burning fossil fuels – something that’s unequivocally supported by scientific evidence^[8,9] as Science Feedback has extensively reviewed in the past (see here).

Beyond greenhouse gas emissions, we’ve already mentioned that fossil fuel surveying is known to disturb whales, and the fossil fuel industry can harm whales in other ways, too. Oil spills, for example, can decimate whale pods. After the Exxon Valdez tanker ran aground in Alaska in 1989, marine biologists documented a 33% and 41% reduction in the population of two killer whale pods exposed to oil spilled from the tanker, respectively^[10]. The Deepwater Horizon spill of 2011 similarly led to sharp declines in the number of whales per sea area in the Gulf of Mexico, over 80% for some species^[11].

The above shows that it is misleading to claim that offshore wind is a threat to whales without evidence, while there are other human activities for which we actually have evidence that they are putting whales at risk.

CONCLUSION

Offshore wind turbines aren’t quiet, but it’s misleading to label their noise as a danger to whales while ignoring other noise sources. Wind turbines are quieter than heavy winds or passing ships, which studies have shown drown out wind turbine noise. The noise from seafloor surveys is generally not considered loud enough to be harmful. There’s no evidence that offshore wind has any relation to the unusual number of whales who have been killed or injured off the U.S. Atlantic Coast since 2016.

There’s a lot of research ongoing to better understand how exactly whales respond to offshore wind turbines. But we know it’s misleading to suggest wind turbines are a primary cause of harm when the fossil fuel industry inflicts far greater harm upon whales – both directly and indirectly, through the climate change caused by burning fossil fuels. In large part, we’re building so many offshore wind turbines to reduce the world’s reliance on those very fossil fuels. When anti-offshore-wind campaigners rally in the name of the whales even as they’re getting support from fossil fuel interests, they’re creating a conflict of interest.

REFERENCES

1. Tougaard et al. (2020) How loud is the underwater noise from operating offshore wind turbines? The Journal of the Acoustic Society of America.
2. Erbe et al. (2019) The Effects of Ship Noise on Marine Mammals—A Review. Frontiers in Marine Science.
3. Ruppel et al. (2022) Categorizing Active Marine Acoustic Sources Based on Their Potential to Affect Marine Animals. Journal of Marine Science & Engineering.
4. van der Hoop et al. (2012) Assessment of Management to Mitigate Anthropogenic Effects on Large Whales. Conservation Biology.
5. Knowlton et al. (2015) Effects of fishing rope strength on the severity of large whale entanglements. Conservation Biology.
6. Allison and Bassett. (2015) Climate change in the oceans: Human impacts and responses. Science.
7. Peters et al. (2022) On the rise: Climate change in New Zealand will cause sperm and blue whales to seek higher latitudes. Ecological Indicators.
8. IPCC. (2021) Sixth Assessment Report.
9. Zhong and Haigh. (2013) The greenhouse effect and carbon dioxide. Royal Meteorological Society Weather.
10. Matkin et al. (1998) Ongoing population-level impacts on killer whales Orcinus orca following the ‘Exxon Valdez’ oil spill in Prince William Sound, Alaska. Marine Ecology Progress Series.
11. Frasier et al. (2024) A decade of declines in toothed whale densities following the Deepwater Horizon oil spill. Communications Earth & Environment.